Google Meet Mute Toggler

For muting and unmuting Google Meet from the extension icon in the Chrome browser, no matter what tab you're currently looking at.

Features
* Toggle mute in your active Google Meet no matter what tab you're looking at
* Extension icon is green when you're in an active Google Meet and unmuted, red when muted, and otherwise gray
* You'll get an error message if you have more than one Meet open
* You can toggle the mute button on a Meet join page but it won't do much
* If you have a Meet open and toggle muting from within the application or using your keyboard, the extension icon will register this and change color appropriately (checks ever 3 seconds)

See code at https://github.com/jasonketola/Google-Meet-Mute-Toggler.